1. Field of the Invention
The present invention relates to maintaining airflow in order to cool electronic components. Specifically, the invention relates to apparatus and systems to maintain airflow over electronic components when an air moving device is absent.
2. Relevant Art
The electronics industry is constantly striving for increased performance in electronic products. The increased performance is commonly achieved through higher and higher levels of integration, resulting in the use of components that dissipate more heat per unit volume. As the number of components increases within a given computer, the amount of heat generated by electronic components also increases. The increase in generated heat per unit volume has not been tracked by an equal reduction in power dissipation for the individual components. For example, on densely populated circuit boards, the power dissipation per unit area continues to increase.
Many electronic components are designed to work at relatively low temperatures. Typically, heat removal is achieved by blowing cool air over the components with a fan. Some configurations cool by creating high pressure within the enclosure, using a fan to draw cool air into the enclosure, and direct the cool air over heat transfer components as the air seeks a lower pressure exhaust orifice. Other configurations cool by creating low pressure within the enclosure using a fan to exhaust hot air, thereby drawing cool air into an inlet orifice and over heat transfer components on the way to the exhaust orifice.
As the number of components per printed circuit assembly has increased, the amount of heat dissipated per component has increased, and the density of printed circuit assemblies in rack mounted equipment has increased, traditional single fan cooling is no longer sufficient to effectively remove heat. Computer manufacturers have subsequently used more powerful fans and blowers and employed multiple air moving devices to create the airflow necessary to remove the heat from the electronics enclosure.
Typically, air moving devices have moving parts and tend to have a high duty cycle. Low-cost air moving devices are often used to reduce system cost. As a result, air moving devices often have a lower reliability than other components of a typical computer system. In addition, air moving devices often create acoustic noise, which noise tends to increase over time with wear and cause annoyance to users and maintenance personnel.
The aforementioned characteristics often lead to frequent replacement of the air moving devices. Since removal of an air moving device does not directly effect operation of the system, the air moving device is frequently replaced without turning off system power. Even if other air moving devices remain operational during replacement, a gap left by removing the defective air moving device often disturbs air flow and may permit cool air to escape from the enclosure without removing heat generated by the electronic components. If many air moving devices are present, some air moving devices may be removed without immediate replacement.
When airflow is inadequate to cool electronic components even for just a few moments, some electronic components may sense a thermal runaway condition and shutdown—resulting in risky and potentially costly system crashes. Other components may be damaged or degraded. Due to the risks associated with inadequate airflow, there is a need to maintain adequate airflow during replacement. Accordingly, there is a need for a mechanisms and systems that maintain proper airflow over heat generating components while an air moving device is absent.